Food packages are generally provided with an opening device in order to facilitate discharging of the enclosed food product. The opening device may either be an irreversible opening, i.e. once the package is opened it may not be closed, or a recloseable opening device. In order to extend the shelf-life and quality of the food product the latter is often desired. A common way of providing a recloseable opening device is to arrange a threaded neck including a pouring spout on the upper part of the package. The threaded neck is designed such that it may receive a cap, including internal threads, such that the cap is capable of being unscrewed from the neck. Since the cap covers the open spout of the neck, the enclosed food product is protected from the outer environment and the quality of the product may thus be preserved during some time.
Although the above solution provides an improvement over the irreversible openings which always remain open, it is still possible for polluted media to enter the interior of the package via the neckcap interface, e.g. via the threads. Hence, further improvements have been proposed for sealing the open spout of the neck when the package is stored.
WO9640568 describes a cap and neck assembly, wherein a flexible sheet is connected to the interior of the cap such that is covers the open spout when the cap is screwed tightly onto the neck.
As food package necks are often molded as plastic pieces, molding joints are always present on the exterior surfaces of the neck. This reduces the efficiency of the described sheet since it will be difficult to provide adequate sealing over such non-uniform joints. Further, tolerances of the neck and cap will also affect the quality of the sealing.
U.S. Pat. No. 4,405,054 describes a separate member which is arranged between the cap and the neck for providing additional sealing of the open spout of the neck. Such solution is not very user friendly, since an additional and separate member must be used in order to achieve the desired sealing.
In view of the prior art solutions, there is a need for a membrane which provides required sealing of an open spout of a neck for preserving the quality of a food product enclosed within a food package, as well as pro-longing the shelf life of the food product.